1. Field of the Invention
The present invention relates to a head suspension, and particularly to a structure of a head suspension for supporting a magnetic head to read/write data from and on a magnetic disk in an oscillation-type actuator which is used in a magnetic disk apparatus. The magnetic disk apparatus us used as an external storage device for a computer.
2. Description of the Prior Art
Recently, track pitches have been made smaller to increase the storage capacity in a magnetic disk apparatus, and accordingly, the frequency band to control the position of a magnetic head which moves on tracks has become higher. In control using such a high frequency band, it is necessary for the frequency of the mechanical resonance point of the suspension to be high so as not to make the controlling frequency of the head suspension operate the head at the mechanical resonance frequency of the suspension. Namely, a high resonant frequency head suspension is required.
To enhance the resonante frequency of the head suspension to operate the magnetic head, it has been conventionally proposed to increase the thickness of the head suspension entirely or partially, to welding two plates in order to partially increase the thickness of the head suspension, or to provide ribs on the head suspension. Namely, in the prior art, the frequency of the resonance point is enhanced by increasing a spring constant of the head suspension.
However, such solution in the prior art increases the mass of the whole suspension, thus resulting in an influence on floating of a magnetic head slider which is attached to a tip of the head suspension. Namely, the rigidity of the head suspension in the upward and downward direction is so large that uneven floating takes place, or the mass of the whole suspension is increased, thus leading to a reduce shock resistance. An increase in the mass of the suspension makes large a drive system to drive the head suspension and increases the power consumption thereof.
To solve the problems of the prior art, it has been proposed that two anisotropic fiber-reinforced composite layers are used to connect the head slider of the head suspension and a load beam portion of a support of the head slider (see Japanese Kokai No. 8-212741).
However, in a head suspension structure described in Kokai No. 8-212741 in which the fibers are laminated with the orientations degree intersecting at 90 degrees, no optimization of the laminate structure is obtained. Therefore, the resonance frequency of the head suspension in the seeking direction tends to be lower than that of a conventional head suspension using SUS material. Also, there is a possibility that the rigidity of the head suspension in the upward and downward direction is increased.